Note that if the Version argument is dynamic, the
decoder should try to figure out the actual version from the
message itself and then use the proper decoder, e.g. version 1.
If on the other hand the Version argument is an integer,
it means that this is the expected version of the message and
the decoder for that version should be used.

The purpose of this function is to do a minimal decode of
Megaco message. A successfull result is a 'MegacoMessage'
in which only version and mid has been initiated. This function
is used by the megaco_messenger module when the
decode_message/3 function fails to figure out the mid
(the actual sender) of the message.

Note again that a successfull decode only returns a
partially initiated message.

Encode megaco action requests. This function is called when
the user calls the function
encode_actions/3.
If that function is never used or if the codec cannot support this
(the encoding of individual actions), then return with error reason
not_implemented.

Module:encode_action_reply(EncodingConfig, Version, AR) -> OK | Error

EncodingConfig = list()

Version = integer()

AR = action_reply()

OK = {ok, Bin}

Bin = binary()

Error = {error, Reason}

Reason = not_implemented | OtherReason

OtherReason = term()

Encode a megaco action reply. If this, for whatever reason,
is not supported, the function should return the error reason
not_implemented.

This function is used when segmentation has been configured.
So, for this to work, this function must be fully
supported!